5th wheel hitch position in the bed

I think I'm going with the trailer pin weight up front as far forward in the bed as I can get and enough to clear the cab as it seems that the weight forward of the rear axels will add some weight to the front axel, not much but, simple as it may seem, it as a whole, the balance of the tow rig seems to be the the issue also. I know that the weight distribution of the trailer itself on the tongue has it limits. Geometrically does it make sense? I have carried as much as 5000+ in the bed with this truck and as to Kingpin weight, this is not my biggest concern because it will never be that heavy. Over all it is stability that I am looking for. I have those 4 tires in the back of that truck that makes a difference, I can't see why it would not be but the position of the hitch head is again my concern. I understand that a light pin weight on the trailer is not good either as if you loaded heavy in the rear of the trailer. So the overall weight of the tow rig should have how much percentage of weight on the pin and where in position inside of the bed of the truck? That is my question. Example: so I have a toy hauler VS. a regular domestic version. If I'm hauling toys in the rear which is a lot heavier.... weight distribution changes right? I'm just trying to understand it all and not trying to be a pain in the butt...this is new to me and I need the real world experience to tell me I'm crazy out of my mind to overthink it but no question is a stupid question only ignorant mistakes can be avoided.. so forgive me for not knowing...any help...helps.